LYMPH. 103 



Blood-plates are also called blood-plaques or platelets, cor- 

 puscles of Bizzozero, and haeruatoblasts (Fig. 42). These are 

 small, colorless, hyaline, 

 homogeneous bodies, of 

 spherical or discoid shape, -.%:: 



between 2 and 4 micromil- 

 limetres in diameter, num- 

 bering 200,000 to 400,000 

 in each cubic millimetre of 

 normal blood. On exposure 

 to the air they quickly dis- 

 integrate and disappear, so 

 that special precautions are Q 



necessary in taking a speci- Blood-plates. 



men of blood to preserve 



them. They occur singly, or often grouped together, in the 

 vicinity of granular matter, probably the debris of disinte- 

 grated ""plaques. They often form centres from which fila- 

 ments of coagulating fibrin radiate, and they may have some 

 relation to the coagulation of the blood. They have been 

 called hnematoblasts under the idea that they are developing 

 forms of red blood-corpuscles, a supposition that has not been 

 confirmed. Their origin, purpose, and significance are not 

 definitely known. 



Lymph, the fluid which flows in the lymphatic system, con- 

 sists of a fluid, the serum or plasma, suspended in which are 

 free cells, the lymph-corpuscles, and particles of fat. The 

 plasma, or liquor lymphae, is similar to that of the blood. 

 The lymph-corpuscles are leukocytes, like those of the blood. 

 Some of them are white corpuscles that have migrated from 

 the capillaries and been taken up from the tissues by the 

 lymph-stream ; large numbers of them, however, are of the 

 small mononuclear type, and are lymphoid cells carried out 

 of the adenoid tissues through which the lymph-currents pass. 

 The chyle is that portion of the lymph that is collected in the 

 lacteals and intestinal lymphatics ; it is of the nature of an 

 emulsion, opaque and white, from the presence in the plasma 

 of large numbers of minute particles of fat absorbed from 

 the intestines. 



